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Updated: Nov 25, 2025
Genotyping of Staphylococcus aureus by Ribosomal Spacer PCR RS-PCR
Published on: November 4, 2016
Methicillin-resistant Staphylococcus aureus (MRSA) associated with mastitis among water buffaloes in the Philippines
Alona T Badua1,2, Sukolrat Boonyayatra1, Nattakarn Awaiwanont1
1Department of Food Animal Clinic, Faculty of Veterinary Medicine, Chiang Mai University, Mae Hia, Muang, 50100 Chiang Mai, Thailand.
Abstract:
Methicillin-resistant Staphylococcus aureus (MRSA) from dairy animals could pose a public health concern in the population. The study was designed to determine the prevalence of S. aureus and MRSA associated with mastitis among water buffaloes in the central part of Luzon island, the Philippines, and to investigate its associated factors. Three hundred and eighty-four water buffaloes were examined for mastitis using California mastitis test (CMT). Composite milk samples (n = 93) were collected from buffaloes showing positive reaction with CMT. S. aureus was identified from milk samples using biochemical tests. Cefoxitin disk diffusion assay and PCR detecting mecA gene were performed to identify MRSA isolates. Disk diffusion assay was used to investigate the antimicrobial resistance against 9 antibiotics. The prevalence of S. aureus was 41.94% (39/93). MRSA isolates resistant to cefoxitin were at 25.81% (24/93) but only 37.5% (9/24) harbored the mecA gene. All 24 MRSA isolates were resistant to penicillin while the majority were susceptible to clindamycin, trimethoprim-sulfamethoxazole, gentamycin, tetracycline, rifampicin, ciprofloxacin and chloramphenicol with intermediate susceptibility to erythromycin. Furthermore, 37.5% of the isolates were found resistant to two or more antibiotics. Animal-level factor associated with MRSA infection was the history of mastitis (OR = 3.18, CI = 1.03-9.79, p = 0.040). Herd-level factors associated with the detection of MRSA in milk included herd size (OR = 4.24, CI = 1.05-17.07, p = 0.042) and the presence of other animals (OR = 0.15, CI = 0.04-0.58, p = 0.006). High prevalence of intramammary infection with S. aureus and MRSA in dairy buffaloes was observed in the region. This finding raises the concern of preventing zoonotic spread of MRSA.
Insights
Methicillin-resistant Staphylococcus aureus (MRSA) is prevalent in dairy buffaloes in the Philippines, posing a public health risk. This study highlights the need for surveillance and control measures to prevent zoonotic transmission of MRSA.
Area of Science:
- Veterinary Microbiology
- Public Health
- Zoonotic Diseases
Background:
- Methicillin-resistant Staphylococcus aureus (MRSA) in dairy animals is a potential public health concern.
- Dairy buffaloes are a significant source of milk in many regions, including the Philippines.
- Understanding the prevalence and factors associated with MRSA in dairy buffaloes is crucial for disease control.
Purpose of the Study:
- To determine the prevalence of Staphylococcus aureus and MRSA in water buffaloes with mastitis in the Philippines.
- To identify animal-level and herd-level factors associated with MRSA infection in dairy buffaloes.
- To assess the antimicrobial resistance patterns of MRSA isolates from dairy buffaloes.
Main Methods:
- California Mastitis Test (CMT) was used to screen for mastitis in 384 water buffaloes.
- Milk samples (n=93) from CMT-positive buffaloes were analyzed for Staphylococcus aureus using biochemical tests.
- MRSA was identified by cefoxitin disk diffusion and PCR for the mecA gene; antimicrobial resistance was tested against nine antibiotics.
Main Results:
- Staphylococcus aureus prevalence was 41.94%, with MRSA found in 25.81% of samples.
- Only 37.5% of cefoxitin-resistant isolates harbored the mecA gene, indicating potential discrepancies in detection.
- MRSA isolates showed high resistance to penicillin but susceptibility to other antibiotics; 37.5% were multidrug-resistant.
- History of mastitis (OR=3.18), herd size (OR=4.24), and presence of other animals (OR=0.15) were associated with MRSA detection.
Conclusions:
- A high prevalence of Staphylococcus aureus and MRSA intramammary infections was observed in dairy buffaloes in the study region.
- The findings underscore the importance of monitoring and controlling MRSA in dairy animal populations to mitigate zoonotic transmission risks.
- Further research is needed to clarify the role of the mecA gene in MRSA detection and to develop effective intervention strategies.
